Chapter 9: Cellular Respiration and Fermentation

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Chapter 9 Cellular Respiration and Fermentation

• Section 1
• Cellular Respiration An Overview

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A. Chemical Energy and Food

• Respiration- Opposite of Photosynthesis
• Breaks down the food
• we eat into ATP for
• cellular activity and
• maintenance of
• homeostasis
• Energy conversion
• Sun Photosynthesis Glucose-RespirationEnergy for
  Activity

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(No Transcript)
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Therefore- Photosynthesis Sunlight CO2
H2O---------- C6H12O6 6O2 And.. Respirat
ion C6H12O6 6O2------6CO2 6H20 ATP Are
energy conversions responsible for
converting..(Finish this statement )
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B. Aerobic v Anaerobic Respiration

• Respiration is responsible for producing energy
  for cellular activity
• It is much more efficient to break down food in
  order to liberate energy in the presence of
  OXYGEN
• This means it is AEROBIC- with O2
• Some organisms live in ANOXIC environments
  (Without Oxygen)
• These bacteria are known as
• OBLIGATE ANAEROBES-oxygen is harmful to them

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• Some anaerobes can survive for short periods of
  time in the presence of oxygen-
• They are called Facultative Anaerobes
• ex- Brewers Yeast
• Most Aerobes can survive for very short periods
  of time in low oxygen conditions

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• People/Humans prefer to respire aerobically-
  This is why we breathe!!
• From time to time we respire anaerobically- like
  after intense exercise, like weight lifting and
  sprinting- (This is why we are often out of
  breathe afterwards)
• When our bodies anaerobically respire for too
  long we get cramps due to build up of lactic acid
• This does damage to tissue and will not sustain
  us for long

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C. Glycolysis!

• Both Aerobic and Anaerobic Respiration begin with
  Glycolysis!!
• Glycolysis- breakdown of Glucose
• When Glucose is broken down it becomes a three
  Carbon molecule called Pyruvate a.k.a Pyruvic
  Acid
• This takes place in the cytoplasm (outside the
  Mitochondria)

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Glycolysis
2 Phases Energy Investment (It takes money
to make money) Initial Cost of 2 ATP in order to
break apart glucose Energy Payoff- By
breaking down glucose we form 4 ATP Net Gain of 2
ATP
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Glycolysis

• Inputs of Glycolysis
• Glucose- all food is broken down through
  digestion into simple sugars such as glucose
• ATP- Initial Energyto break apart glucose
  into PGAL- Two 3 Carbon Intermediates
• Outputs of Glycolysis
• ATP- 2 ATP Molecules are produced Two
  molecules of Pyruvate- Pyruvic Acid
• 2 Molecules of NADH- Electron carriers

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Glycolysis
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Glycolysis

• The Fate of Pyruvic Acid depends on the presence
  of Oxygen
• If O2 is present Aerobic Respiration occurs aka
  Respiration
• If O2 absent- Anaerobic Repiration occurs- aka
  Fermentation

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D. Aerobic Cellular Repiration

• Happens in the Presence of Oxygen
• Begins with the products of Glycolysis two
  molecules of Pyruvic Acid (C-C-C)
• The Pyruvic Acid diffuses into the Mitochondrial
  Matrix and enters the Citric Acid Cycle- aka
  Krebs Cycle
• - In the CAC Pyruvic Acid is broken apart, one
  Carbon at a time and released as CO2
• - As it is broken energy is converted (2ADP-
  2ATP)
• and electron energy is stored (4NAD--- 4NADH
  and FAD ----FADH)
• - This happens twice ( 8 NADH and 2 FADH
  Total- that is 20 Electrons)

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• 1. Citric Acid Cycle
• a. Begins with Pyruvic Acid (C-C-C)
• b. Enzymes remove 1
• Carbon- leaving behind
• a two carbon
• compound called
• Acetyl/Acetic Acid
• This joins with another
• enzyme (Co A) which
• is 4 Carbons Long!
• Becomes Acetyl Co A
• (6 Carbons)
• This makes it easier to separate the last
  two carbons from Pyruvic Acid and expel them as
  CO2 while stealing their energy in the form of
  electrons- Lots of NADH and FADH

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Citric Acid Cycle
Every time a Carbon is removed- 2 High Energy
Electrons are Freed and stored by NAD and FAD
Total ATP 2 Total electron Pairs 10
Remember- this happens twice!!! Glucose was
broken down into two mols of Pyruvic Acid!
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• Citric Acid Cycle
• Inputs 2 Pyruvic Acids (Glycolysis)
• Outputs CO2 (Expelled as waste)
• 2 ATP (very little energy- used
  for cellular activity)
• NADH and FADH (To be used later in order
  to make a lot of ATP)

All of these electrons are going to be used
during the next phase (Electron Transport) to
synthesize ATP
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• Electron Transport Chain (ETC)
• Electrons carried to the inner
• membrane by NADH and FADH
• are dropped off at the beginning
• As the electrons are passed
• along, their energy is used to
• pump H ions out of the matrix
• and into the intermembrane space
• creating a Conc. Gradient
• The only way back into the matrix for H ions is
  through a protein called ATP Synthase.
• As H move through ATP Synthase like water
  through a dam, energy is used to convert ADP to
  ATP.
• Each pair of electrons can produce between two
  and three ATPs (Depends on if they came from NADH
  or FADH)
• 9NADH 28 ATP
• 2FADH 4 ATP
• Total of 32 ATPs created during ETC!!!!

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Electron Transport Chain and ATP Synthase
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Total ATP Production

• Glycolysis- 2 ATP
• Citric Acid Cycle- 2ATP
• Electron Transport-32 ATP
• TOTAL 36 ATP
• Not bad for one molecule of glucose!!

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D. Anaerobic Respiration

• Occurs without Oxygen Present
• Also known as Fermentation

Tequila
Beer
Whiskey
Cramping
What do they all have in common? (Three Things)
Fermentation
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Fermentation

• 1. Alcoholic Fermentation

1. Occurs in Yeast when Oxygen is not present to
   clear the ETC and CAC Cycle
2. Electrons cannot be passed into Krebs cycle so
   they get passed back to Pyruvic Acid
3. Forms new products Ethyl Alcohol and Carbon
   Dioxide

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Alcoholic Fermentation

Ethyl Alcohol
Pyruvic Acid
Count the Atoms- What goes in should come out!!!!
Carbon Dioxide
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• 2. Lactic Acid Fermentation

a. Occurs in all animal species b. When
Oxygen is not present- electrons get passed back
to Pyruvic acid and attach in a different
location (Look at Hs)- Forms Lactic Acid c.
Responsible for muscle soreness and cramping
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Lactic Acid Fermentation

Pyruvic Acid